Yang Zhenle, Su Xinhua, Wu Feng, Gong Yandao, Kuang Tingyun
Key Laboratory of Photosynthesis and Environmental, Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.
J Photochem Photobiol B. 2005 Feb 1;78(2):125-34. doi: 10.1016/j.jphotobiol.2004.10.003.
Phosphatidylglycerol (PG) is the only anionic phospholipid in photosynthetic membrane and the important component of photosystem I (PSI). In this study, the interaction of PG with PSI particle from spinach was investigated by using reconstitution method. The results from the properties of electron transport, fluorescence emission, turbidity, and protein secondary structures in PSI complex incorporated into PG liposomes revealed the existence of PSI-PG interactions. A stimulation and an inhibition of oxygen uptake in PSI particle at a low and higher PG/chlorophyll mass ratio, respectively, were observed. Moreover, an additional enhancement and depression of electron flow in the PSI-PG complexes were occurred in the reaction medium containing CaCl2 at concentrations below and above 5 mM, the aggregation threshold of the reconstituted membranes, respectively. The results demonstrated that the maintenance of the structural optimization was needed for a stimulation of electron transport at a low PG/PSI mass ratio, while a decay of this PSI activity at high PG/PSI ratio was the result of inhibition of the energy transfer from LHCI to PSI reaction center induced by the dissociation of LHCI-680.
磷脂酰甘油（PG）是光合膜中唯一的阴离子磷脂，也是光系统I（PSI）的重要组成部分。在本研究中，采用重组方法研究了PG与菠菜PSI颗粒的相互作用。将PSI复合物掺入PG脂质体后，对其电子传递、荧光发射、浊度和蛋白质二级结构特性的研究结果揭示了PSI与PG之间相互作用的存在。观察到在低PG/叶绿素质量比和高PG/叶绿素质量比时，PSI颗粒对氧气吸收分别有刺激作用和抑制作用。此外，在反应介质中，当CaCl2浓度分别低于和高于5 mM（重组膜的聚集阈值）时，PSI-PG复合物中的电子流分别出现额外的增强和减弱。结果表明，在低PG/PSI质量比下刺激电子传递需要维持结构优化，而在高PG/PSI比下PSI活性的下降是由于LHCI-680解离导致LHCI向PSI反应中心的能量转移受到抑制的结果。
